Light-emitting module and planar light source

ABSTRACT

A light-emitting module includes: a light source; a light guide plate including an upper surface and a lower surface, the lower surface being at a side opposite to the upper surface, the light guide plate being configured to guide light from the light source; a wavelength conversion sheet located at an upper surface side of the light guide plate; a first light-reflective member located at a lower surface side of the light guide plate, the first light-reflective member including: a first resin member, and a first reflector, where a refractive index of the first reflector is lower than a refractive index of the first resin member; and a second light-reflective member located at a lower surface side of the first light-reflective member, wherein the second light-reflective member includes: a second resin member, and a second reflector, where a refractive index of the second reflector is higher than a refractive index of the second resin member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/374,066, filed on Jul. 13, 2021, which claims priority to JapanesePatent Application No. 2020-124395, filed on Jul. 21, 2020, JapanesePatent Application No. 2021-52755, filed on Mar. 26, 2021, and JapanesePatent Application No. 2021-075288, filed on Apr. 27, 2021, thedisclosures of which are hereby incorporated by reference in theirentireties.

BACKGROUND

The present disclosure relates to a light-emitting module and a planarlight source.

Light-emitting modules that combine a light guide plate and alight-emitting element such as a light-emitting diode or the like arewidely utilized in planar light sources such as, for example, backlightsof liquid crystal displays, etc. For example, JP-A 2019-61929 (Kokai)discusses a backlight device that includes an LED substrate including areflective sheet and multiple light-emitting diodes, and a diffuserplate that faces the LED substrate.

SUMMARY

The present disclosure is directed to a light-emitting module and aplanar light source that can be thin and can have higher reflectance ata lower surface side of a light guide plate.

According to one embodiment, a light-emitting module includes: a lightsource; a light guide plate including an upper surface and a lowersurface, the lower surface being at a side opposite to the uppersurface, the light guide plate guiding light from the light source; afirst light-reflective member located at the lower surface side of thelight guide plate; and a second light-reflective member located at alower surface side of the first light-reflective member. The firstlight-reflective member includes a first resin member, and a firstreflector having a lower refractive index than the first resin member.The second light-reflective member includes a second resin member, and asecond reflector having a higher refractive index than the second resinmember.

According to certain embodiments of the preset disclosure, alight-emitting module and a planar light source can be thin and can havehigher reflectance at a lower surface side of a light guide plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a planar light source of oneembodiment of the invention;

FIG. 2 is a schematic cross-sectional view along line II-II of FIG. 1;

FIG. 3A is a schematic cross-sectional view of a first light-reflectivemember of one embodiment of the invention;

FIG. 3B is a schematic cross-sectional view of a second light-reflectivemember of one embodiment of the invention;

FIG. 4A is a schematic cross-sectional view of a light source of oneembodiment of the invention;

FIG. 4B is a schematic cross-sectional view of a light source of anotherembodiment of the invention;

FIG. 4C is a schematic cross-sectional view of a light source of anotherembodiment of the invention;

FIG. 5 to FIG. 13 are schematic cross-sectional views showing a methodfor manufacturing the planar light source of one embodiment of theinvention;

FIG. 14 is a schematic cross-sectional view of one portion of a planarlight source according to another embodiment of the invention;

FIG. 15 is a schematic cross-sectional view of one portion of a planarlight source according to another embodiment of the invention; and

FIG. 16 is a graph illustrating measurement results of the reflectanceby wavelength for three test samples.

DETAILED DESCRIPTION

Embodiments will now be described with reference to the drawings. Thedrawings schematically show embodiments. The scale, spacing, positionalrelationships, and the like of the members may be exaggerated. Portionsof the members may be not-illustrated. End views that show only cuttingsurfaces may be used as cross-sectional views. The same elements in thedrawings are marked with the same reference numerals.

FIG. 1 is a schematic plan view of a planar light source 300 of oneembodiment of the invention. FIG. 1 illustrates the light-emittingsurface of the planar light source 300 in a plan view. In FIG. 1, twomutually-orthogonal directions parallel to the light-emitting surface ofthe planar light source 300 are designated as an X-direction and aY-direction. For example, the planar light source 300 has a rectangularexterior shape that includes two sides extending along the X-directionand two sides extending along the Y-direction.

The planar light source 300 can include one or multiple light sources20. When the planar light source 300 includes multiple light sources 20,a partitioning groove 14 partitions between the light sources 20. Oneregion that is partitioned by the partitioning groove 14 is taken as alight-emitting region 301. For example, one light-emitting region 301can be used as the driving unit of local dimming. Multiple light sources20 may be located in one light-emitting region 301 that is partitionedby the partitioning groove 14.

FIG. 1 illustrates the planar light source 300 that includes sixlight-emitting regions 301 partitioned into two rows and three columns.The number of the light-emitting regions 301 included in the planarlight source 300 is not limited to the number shown in FIG. 1. Theplanar light source 300 may include one light source 20; in such a case,one planar light source 300 includes one light-emitting region 301. Aplanar light source device that has a larger surface area can be formedby arranging the multiple planar light sources 300.

FIG. 2 is a schematic cross-sectional view along line II-II of FIG. 1.The planar light source 300 includes a light-emitting module 100 and awiring substrate 200.

The light-emitting module 100 includes a light guide plate 10, the lightsource 20, a first light-reflective member 41, a second light-reflectivemember 42, a third light-reflective member 43, a firstlight-transmitting member 80, and a first light-modulating member 90.

Light from the light source 20 is guided by the light guide plate 10;and the light guide plate 10 is transmissive to the light emitted by thelight source 20. The light source 20 includes a light-emitting element21. The light that is emitted by the light source 20 includes at leastthe light emitted by the light-emitting element 21. For example, whenthe light source 20 includes a phosphor, the light that is emitted bythe light source 20 also includes the light emitted by the phosphor. Itis favorable for the transmittance of the light guide plate 10 for thelight from the light source 20 to be, for example, not less than 80%,and more favorably not less than 90%.

For example, a thermoplastic resin such as acrylic, polycarbonate,cyclic polyolefin, polyethylene terephthalate, polyester, or the like, athermosetting resin such as epoxy, silicone, or the like, glass, etc.,can be used as the material of the light guide plate 10.

The light guide plate 10 includes an upper surface 11 that is used asthe light-emitting surface of the planar light source 300, and a lowersurface 12 at the side opposite to the upper surface 11. The light guideplate 10 also includes a hole portion. In the example shown in FIG. 2,the hole portion is a through-hole 13 that extends from the uppersurface 11 to the lower surface 12.

It is favorable for the thickness of the light guide plate 10 to be, forexample, not less than 200 μm and not more than 800 μm. In the thicknessdirection, the light guide plate 10 may include a single layer, or astacked body of multiple layers. When the light guide plate 10 includesa stacked body, transmissive bonding members may be provided between thelayers. The layers of the stacked body may include different types ofmajor materials. For example, a thermoplastic resin such as acrylic,polycarbonate, cyclic polyolefin, polyethylene terephthalate, polyester,or the like, a thermosetting resin such as epoxy, silicone, etc., can beused as the material of the bonding member.

As shown in FIG. 1, for example, the through-hole 13 can be circular ina plan view. Also, for example, the through-hole 13 can be an ellipse ora polygon such as a triangle, a rectangle, a hexagon, an octagon, etc.,in a plan view.

The partitioning groove 14 that surrounds at least one light source 20in a plan view is formed in the light guide plate 10. As shown in FIG.1, it is favorable for the light guide plate 10 to include thepartitioning groove 14 having a lattice configuration that includes thepartitioning groove 14 extending in a straight line in the X-directionand the partitioning groove 14 extending in the Y-direction.

FIG. 2 illustrates the partitioning groove 14 that extends from theupper surface 11 to the lower surface 12 of the light guide plate 10 andreaches the first light-reflective member 41. The partitioning groove 14may be a bottomed groove that is open at the upper surface 11 side ofthe light guide plate 10 and includes a bottom that does not reach thelower surface 12. In such a case, it is favorable for the bottom of thepartitioning groove 14 to be proximate to the lower surface 12. Or, thepartitioning groove 14 may be a bottomed groove that is open at thelower surface 12 side and includes a bottom that does not reach theupper surface 11.

The third light-reflective member 43 can be located in the partitioninggroove 14. Although the third light-reflective member 43 is filled intothe partitioning groove 14 so that the upper surface of the thirdlight-reflective member 43 is a flat surface in FIG. 2, for example, theupper surface of the third light-reflective member 43 may be a concaveor convex curved surface. The third light-reflective member 43 may coverat least a portion of the inner side surface of the partitioning groove14 in a layer configuration; and a space may be formed in a portion ofthe interior of the partitioning groove 14. For example, a resin memberthat includes a light-diffusing agent can be used as such a thirdlight-reflective member 43. For example, a TiO₂ particle is an exampleof the light-diffusing agent. Also, particles of Nb₂O₅, BaTiO₃, Ta₂O₅,Zr₂O₃, ZnO, Y₂O₃, Al₂O₃, MgO, BaSO₄, etc., are examples of thelight-diffusing agent. For example, a metal member of Al, Ag, etc., maybe used as the third light-reflective member 43. The entire interior ofthe partitioning groove 14 may be air.

To reduce uneven luminance, for example, the upper surface 11 of thelight guide plate 10 may include a protrusion and/or a recess in aregion of low luminance.

The third light-reflective member 43 suppresses light propagationbetween the adjacent light-emitting regions 301. For example, the lightpropagation from a light-emitting region 301 that is in a light-emittingstate to a light-emitting region 301 that is in a non-light-emittingstate is limited. Thereby, local dimming is possible in which each ofthe light-emitting regions 301 is a driving unit.

The first light-reflective member 41 is located at the lower surface 12side of the light guide plate 10. For example, the firstlight-reflective member 41 is bonded to the lower surface 12 of thelight guide plate 10 by a bonding member 71. For example, an epoxyresin, an acrylic resin, an olefin resin, etc., are examples of thebonding member 71.

The second light-reflective member 42 is located at the lower surfaceside of the first light-reflective member 41. For example, the secondlight-reflective member 42 is bonded to the lower surface of the firstlight-reflective member 41.

The first light-reflective member 41 faces the lower surface 12 of thelight guide plate 10 and the lower surface of the light source 20 viathe bonding member 71. In other words, the first light-reflective member41 plugs the opening of the through-hole 13 of the light guide plate 10at the lower surface 12 side. The second light-reflective member 42faces the entire lower surface of the first light-reflective member 41.The second light-reflective member 42 may face a portion of the lowersurface of the first light-reflective member 41. For example, it isfavorable for the second light-reflective member 42 to be located atportions that are relatively distant from the light source 20 inside thelight-emitting region 301 and therefore have a tendency for theluminance to be low (e.g., portions that correspond to the corners ofthe light-emitting region 301 in a plan view).

The first light-reflective member 41 and the second light-reflectivemember 42 are located between the wiring substrate 200 and the lowersurface 12 of the light guide plate 10.

The thickness of the second light-reflective member 42 can be set to beless than the thickness of the first light-reflective member 41. Forexample, the thickness of the first light-reflective member 41 is notless than 20 μm and not more than 300 μm, and favorably not less than 40μm and not more than 250 μm. The thickness of the secondlight-reflective member 42 is not less than 10 μm and not more than 150μm, and favorably not less than 20 μm and not more than 100 μm.

FIG. 3A is a schematic cross-sectional view of the firstlight-reflective member 41.

The first light-reflective member 41 includes a first resin member 41 a,and a first reflector 41 b that has a lower refractive index than thefirst resin member 41 a. The first resin member 41 a is transmissive tothe light emitted by the light source 20 and is, for example, a resinmember such as a polyethylene terephthalate (PET) resin, an olefinresin, an acrylic resin, a silicone resin, a urethane resin, an epoxyresin, etc. The first reflector 41 b is, for example, a bubble. Also,for example, silica, hollow silica, CaF₂, MgF₂, etc., can be used as thefirst reflector 41 b.

FIG. 3B is a schematic cross-sectional view of the secondlight-reflective member 42.

The second light-reflective member 42 includes a second resin member 42a, and a second reflector 42 b that has a higher refractive index thanthe second resin member 42 a. The second resin member 42 a has a lowerrefractive index than the first resin member 41 a of the firstlight-reflective member 41. The second resin member 42 a is transmissiveto the light emitted by the light source 20 and is, for example, a resinmember such as an acrylic resin, a silicone resin, a urethane resin, anepoxy resin, a phenol resin, a BT resin, a polyimide resin, aunsaturated polyester resin, etc. The second reflector 42 b is, forexample, a TiO₂ particle. Also, for example, particles of Nb₂O₅, BaTiO₃,Ta₂O₅, Zr₂O₃, ZnO, Y₂O₃, Al₂O₃, MgO, BaSO₄, etc., can be used as thesecond reflector 42 b.

It is favorable for the second light-reflective member 42 to have asmall elastic modulus change for a temperature change of 25° C. to 100°C. For example, it is favorable for the change of the elastic modulus ofthe second light-reflective member 42 at 60° C. to be not more than 60%of the elastic modulus at 25° C., and for the change of the elasticmodulus of the second light-reflective member 42 at 100° C. to be notmore than 80% of the elastic modulus at 25° C. In particular, it isfavorable for the elastic modulus of the second light-reflective member42 at 100° C. to be not less than 10000 Pa and not more than 50000 Pa,and more favorably not less than 20000 Pa and not more than 40000 Pa.Thereby, for example, deviation of the position of the secondlight-reflective member 42 with respect to the first light-reflectivemember 41 due to the heat when curing a conductive paste located insidea hole 401 such as that shown in FIG. 12 can be suppressed; and theoccurrence of cracks in the cured conductive paste (a first conductiveportion 61) can be suppressed.

For example, the refractive index of the first resin member 41 a, thefirst reflector 41 b, the second resin member 42 a, or the secondreflector 42 b according to the embodiment can be measured using an Abberefractometer or the like or estimated from the composition identifiedby Fourier transform infrared spectroscopy analysis, etc. Also, forexample, the refractive index of the first resin member 41 a or thesecond resin member 42 a can be estimated by disposing the first resinmember 41 a or the second resin member 42 a inside a liquid having adesignated refractive index (hereinbelow, called a refractive liquid)and by using an optical microscope to observe the existence or absenceof an interface between the refractive liquid and the first resin member41 a or the second resin member 42 a. In other words, the refractiveindex of the first resin member 41 a or the second resin member 42 a canbe estimated to be near the refractive index of the refractive liquidwhen an interface with the refractive liquid cannot be seen (or isdifficult to see). When the first resin member 41 a, the first reflector41 b, the second resin member 42a, or the second reflector 42 b is acommercial product, the catalog value of the refractive index can beused.

The light source 20 is located inside the through-hole 13 of the lightguide plate 10 on the first light-reflective member 41 with the bondingmember 71 interposed.

FIG. 4A is a schematic cross-sectional view of an example of the lightsource 20.

The light source 20 may be a solitary light-emitting element or may havea structure in which an optical member such as a wavelength conversionmember or the like is combined with a light-emitting element. Accordingto the embodiment as shown in FIG. 4A, the light source 20 includes thelight-emitting element 21, an electrode 23, a cover member 24, a secondlight-transmitting member 25, and a second light-modulating member 26.The light source 20 does not necessarily include the secondlight-modulating member 26 according to the desired light distribution.For example, the second light-modulating member 26 is not necessarilylocated on the second light-transmitting member 25; in other words, theupper surface of the second light-transmitting member 25 can form aportion of the upper surface of the light source 20.

The light-emitting element 21 includes a semiconductor stacked body 22.The semiconductor stacked body 22 includes, for example, a supportsubstrate of sapphire, gallium nitride, or the like, an n-typesemiconductor layer and a p-type semiconductor layer that are located onthe support substrate, a light-emitting layer that is sandwiched betweenthe n-type semiconductor layer and the p-type semiconductor layer, andan n-side electrode and a p-side electrode that are electricallyconnected respectively to the n-type semiconductor layer and the p-typesemiconductor layer. The support substrate may be removed when thesemiconductor stacked body 22 is used. The light-emitting layer may havea structure that includes a single active layer such as a single quantumwell structure (SQW) or a double heterostructure, or a structure thatincludes an active layer group such as a multi-quantum well structure(MQW). The light-emitting layer is configured to emit visible light orultraviolet light. The light-emitting layer is configured to emitvisible light from blue to red. The semiconductor stacked body 22 thatincludes such a light-emitting layer can include, for example,In_(x)Al_(y)Ga_(1-x-y)N (0≤x, 0≤y, and x+y≤1). The semiconductor stackedbody 22 can include at least one light-emitting layer described abovethat can emit light. For example, the semiconductor stacked body 22 mayhave a structure that includes not less than one light-emitting layerbetween an n-type semiconductor layer and a p-type semiconductor layer,or a configuration in which a structure that includes an n-typesemiconductor layer, a light-emitting layer, and a p-type semiconductorlayer in this order are repeated multiple times. When the semiconductorstacked body 22 includes multiple light-emitting layers, thelight-emitting layers may have different light emission peak wavelengthsfor the same light emission peak wavelength. The light emission peakwavelengths being the same means that the fluctuation may be aboutseveral nm. A combination of the light emission peak wavelengths can beselected as appropriate. For example, when the semiconductor stackedbody 22 includes two light-emitting layers, a light-emitting layer thatincludes a combination of blue light and blue light, green light andgreen light, red light and red light, ultraviolet light and ultravioletlight, blue light and green light, blue light and red light, green lightand red light, etc., can be selected. Each light-emitting layer mayinclude multiple active layers having different light emission peakwavelengths or the same light emission peak wavelength.

The second light-transmitting member 25 covers the upper surface andside surface of the light-emitting element 21. The secondlight-transmitting member 25 has the functions of protecting thelight-emitting element 21, performing wavelength conversion and lightdiffusion according to particles added to the second light-transmittingmember 25, etc. Specifically, the second light-transmitting member 25may include a light-transmitting resin and may further include aphosphor. For example, a silicone resin, an epoxy resin, etc., can beused as the light-transmitting resin. An yttrium-aluminum-garnet-basedphosphor (e.g., Y₃(Al, Ga)₅O₁₂:Ce), a lutetium-aluminum-garnet-basedphosphor (e.g., Lu₃(Al, Ga)₅O₁₂:Ce), a terbium-aluminum-garnet-basedphosphor (e.g., Tb₃(Al, Ga)₅O₁₂:Ce), a CCA-based phosphor (e.g.,Ca₁₀(PO₄)₆C₁₂:Eu), an SAE-based phosphor (e.g., Sr₄Al₁₄O₂₅:Eu), achlorosilicate-based phosphor (e.g., Ca₈MgSi₄O₁₆C₁₂:Eu), a nitride-basedphosphor such as a β-sialon-based phosphor (e.g., (Si, A₁)₃(₀, N)₄:Eu),an α-sialon-based phosphor (e.g., M_(z)(Si, Al)₁₂(O, N)₁₆:Eu (however,0<z≤2, and M is a lanthanide element other than Li, Mg, Ca, Y, La, andCe)), an SLA-based phosphor (e.g., SrLiAl₃N₄:Eu), a CASN-based phosphor(e.g., CaAlSiN₃:Eu), a SCASN-based phosphor (e.g., (Sr, Ca)AlSiN₃:Eu),or the like, a fluoride-based phosphor such as a KSF-based phosphor(e.g., K₂SiF₆:Mn), a KSAF-based phosphor (e.g., K₂(Si, Al)F₆:Mn), aMGF-based phosphor (e.g., 3.5MgO.0.5MgF₂.GeO₂:Mn), or the like, aphosphor that has a perovskite structure (e.g., CsPb(F, Cl, Br, I)₃), aquantum dot phosphor (e.g., CdSe, InP, AgInS₂, or AgInSe₂), etc., can beused as the phosphor. One type of phosphor or multiple types ofphosphors may be used as the phosphor added to the secondlight-transmitting member 25.

The KSAF-based phosphor may include a composition represented by thefollowing formula (I).

M₂[Si_(p)Al_(q)Mn_(r)F_(s)]  (I)

In formula (I), M represents an alkali metal and may contain at least K.Mn may be a tetravalent Mn ion. The parameter of p, q, r and s maysatisfy the relationship of “0.9 p+q+r≤1.1, 0<q<0.1, 0<r≤0.2,5.9≤s≤6.1”. Preferably, the parameter of p, q,≤r≤and s may satisfy therelationship of “0.95 p+q+r≤1.05 or 0.97 p+q+r≤1.03, 0<q<0.03,0.002≤q≤0.02 or 0.003≤q≤0.015, 0.005≤r≤0.15, 0.01≤r≤0.12 or 0.015≤r≤0.1,5.92≤s≤6.05 or 5.95≤s≤6.025”. For example, the composition representedby K₂ [Si_(0.946)Al_(0.005)Mn_(0.049)F_(5.995)], K₂[Si_(0.942)Al_(0.008)Mn_(0.050)F_(5.992)], and K₂[Si_(0.939)Al_(0.014)Mn_(0.047)F_(5.986)] can be exemplified. Accordingto such a KSAF-based phosphor, it is possible to obtain red emissionhaving high brightness and a narrow half-value width of the emissionpeak wavelength.

The cover member 24 is located at least at the lower surface of thelight-emitting element 21. The cover member 24 is disposed so that thesurface (in FIG. 4A, the lower surface) of the electrode 23 that iselectrically connected with the light-emitting element 21 is not coveredwith the cover member 24. The cover member 24 is located also at thelower surface of the second light-transmitting member 25 that covers theside surface of the light-emitting element 21.

The cover member 24 is reflective to the light emitted by the lightsource 20. The cover member 24 is, for example, a resin member thatincludes a light-diffusing agent. Specifically, the cover member 24 is asilicone resin, an epoxy resin, or an acrylic resin that includes alight-diffusing agent made of particles of TiO₂, SiO₂, Al₂O₃, ZnO,glass, etc. The cover member 24 may be an inorganic member.

The second light-modulating member 26 is located at the upper surface ofthe second light-transmitting member 25 and controls the amount and/oremission direction of the light emitted from the upper surface of thesecond light-transmitting member 25. The second light-modulating member26 is reflective and transmissive to the light emitted by the lightsource 20. A portion of the light that is emitted from the upper surfaceof the second light-transmitting member 25 is reflected by the secondlight-modulating member 26, and another portion passes through thesecond light-modulating member 26. It is favorable for the transmittanceof the second light-modulating member 26 to be, for example, not lessthan 1% and not more than 50%, and more favorably not less than 3% andnot more than 30%. The luminance directly above the light source 20 isreduced thereby, and the surface fluctuation of the luminance of theplanar light source 300 is reduced. The second light-modulating member26 can include a light-transmitting resin, a light-diffusing agent thatis included in the light-transmitting resin, etc. The light-transmittingresin is, for example, a silicone resin, an epoxy resin, or an acrylicresin. For example, particles of TiO₂, SiO₂, Al₂O₃, ZnO, glass, etc.,are examples of the light-diffusing agent. The second light-modulatingmember 26 may be, for example, a metal member of Al, Ag, or the like, ora dielectric multilayer film. The second light-modulating member 26 maybe an inorganic member.

A sheet-like wavelength conversion member (hereinbelow, called awavelength conversion sheet) that includes the phosphor described abovemay be located on the planar light source 300. A planar light sourcethat emits white light can be obtained by the wavelength conversionsheet absorbing a portion of the blue light from the light source 20 andemitting yellow light, green light, and/or red light. For example, whitelight can be obtained by combining a light source that can emit bluelight and a wavelength conversion sheet that includes a phosphor thatcan emit yellow light. Or, a light source that can emit blue light and awavelength conversion sheet that includes a red phosphor and a greenphosphor may be combined. Or, a light source that can emit blue lightand multiple wavelength conversion sheets may be combined. For example,a wavelength conversion sheet that includes a phosphor that can emit redlight and a wavelength conversion sheet that includes a phosphor thatcan emit green light can be selected as the multiple wavelengthconversion sheets. Or, a light source that includes a light-emittingelement adapted to emit blue light, a light-transmitting memberincluding a phosphor adapted to emit red light, and a wavelengthconversion sheet including a phosphor adapted to emit green light may becombined.

As shown in FIG. 2, the first light-transmitting member 80 is located inthe through-hole 13 of the light guide plate 10. The firstlight-transmitting member 80 is transmissive to the light emitted by thelight source 20; for example, the same resin as the material of thelight guide plate 10 or a resin that has a slightly smaller refractiveindex than the material of the light guide plate 10 can be used.

The first light-transmitting member 80 is located between the sidesurface of the light source 20 and the side surface of the through-hole13. In such a case, it is favorable for the first light-transmittingmember 80 to be located so that a space such as an air layer or the likeis not formed between the first light-transmitting member 80 and theside surface of the light source 20 and between the firstlight-transmitting member 80 and the side surface of the through-hole13. Thereby, the light from the light source 20 can be easily guidedinto the light guide plate 10.

The first light-transmitting member 80 covers the upper surface of thelight source 20 (in the example, the upper surface of the secondlight-modulating member 26). The upper surface of the firstlight-transmitting member 80 can be a flat surface. Or, the uppersurface of the first light-transmitting member 80 can be a concave orconvex curved surface.

The wiring substrate 200 includes an insulating base 50, a first wiringlayer 53 that is located at one surface of the insulating base 50, asecond wiring layer 54 that is located at another surface of theinsulating base 50, and a conductive member 60.

The wiring substrate 200 can further include a first insulating layer 52and a second insulating layer 51. The first insulating layer 52 covers aportion of the first wiring layer 53 and a portion of the surface of theinsulating base 50 at which the first wiring layer 53 is located. Thesecond insulating layer 51 covers the second wiring layer 54 and thesurface of the insulating base 50 at which the second wiring layer 54 islocated. The second light-reflective member 42 is located on the secondinsulating layer 51.

The conductive member 60 includes the first conductive portion 61 and asecond conductive portion 62. The first conductive portion 61 extendsthrough the bonding member 71, the first light-reflective member 41, thesecond light-reflective member 42, the second insulating layer 51, andthe insulating base 50. The first conductive portion 61 is connectedwith the electrode 23 and is positioned under the electrode 23 of thelight source 20 in the thickness direction of the planar light source300.

The second conductive portion 62 covers a portion of the first wiringlayer 53 and is located at a surface of the insulating base 50 that isnot covered with the first insulating layer 52. The second conductiveportion 62 connects the first conductive portion 61 and the first wiringlayer 53. Accordingly, the electrode 23 of the light source 20 iselectrically connected with the first wiring layer 53 via the first andsecond conductive portions 61 and 62 of the conductive member 60.

The first wiring layer 53 and the second wiring layer 54 areelectrically connected to each other at a portion of the planar lightsource 300 other than the cross-sectional portion shown in FIG. 2. Forexample, the first wiring layer 53 and the second wiring layer 54 areconnected by an interconnect extending through the insulating base 50.

The insulating base 50, the first insulating layer 52, and the secondinsulating layer 51 can include, for example, a resin such as polyimide,polyethylene naphthalate, polyethylene terephthalate, etc. The firstwiring layer 53 and the second wiring layer 54 can include, for example,a metal such as copper, aluminum, etc. The conductive member 60 is, forexample, a conductive paste in which a conductive filler is dispersed ina binder resin. The conductive member 60 can include, for example, ametal such as copper, silver, etc., as the filler. The filler isparticulate or flake-like.

The first light-modulating member 90 is located at least on the firstlight-transmitting member 80. The first light-modulating member 90 isreflective and transmissive to the light emitted by the light source 20.The first light-modulating member 90 can include a light-transmittingresin, a light-diffusing agent that is dispersed in thelight-transmitting resin, etc. The light-transmitting resin is, forexample, a silicone resin, an epoxy resin, or an acrylic resin. Forexample, particles of TiO₂, SiO₂, Al₂O₃, ZnO, glass, etc., are examplesof the light-diffusing agent. The first light-modulating member 90 maybe an inorganic member. The first light-modulating member 90 can coverthe entirety or a portion of the upper surface of the firstlight-transmitting member 80.

As shown in FIG. 1, the first light-modulating member 90 overlaps thelight source 20 in a plan view. In the example shown in FIG. 1, thefirst light-modulating member 90 is a larger rectangle than therectangular light source 20 in a plan view. The first light-modulatingmember 90 can be a shape such as a circle, a triangle, a hexagon, anoctagon, etc., in a plan view. As shown in FIG. 2, the firstlight-modulating member 90 may extend onto the upper surface of thefirst light-transmitting member 80 and the upper surface 11 of the lightguide plate 10 at the periphery of the upper surface of the firstlight-transmitting member 80.

In addition to overlapping the light source 20 in a plan view, the firstlight-modulating member 90 also may be interspersed in regions of highluminance of the upper surface 11 of the light guide plate 10 todecrease uneven luminance. For example, the first light-modulatingmember 90 can be interspersed at the vicinity of the partitioning groove14, and more specifically, along the partitioning groove 14.

A portion of the first light-transmitting member 80 is located betweenthe first light-modulating member 90 and the second light-modulatingmember 26 of the light source 20. The first light-transmitting member 80has a higher transmittance for the light emitted by the light source 20than the second and first light-modulating members 26 and 90. Thetransmittance of the first light-transmitting member 80 for the lightemitted by the light source 20 can be in a range that is not more than100%, and is not less than 2 times and not more than 100 times thetransmittance of the second light-modulating member 26 and thetransmittance of the first light-modulating member 90.

The second light-modulating member 26 reflects a portion of the lightthat is emitted directly upward from the light source 20 and passesthrough another portion. Thereby, the luminance of the region directlyabove the light source 20 can be prevented from becoming extremely highcompared to the luminance of the other regions in light-emitting regions301 of the planar light source 300. That is, the uneven luminance of thelight emitted from one light-emitting region 301 partitioned by thepartitioning groove 14 can be reduced. It is favorable for the thicknessof the first light-modulating member 90 to be not less than 0.005 mm andnot more than 0.2 mm, and more favorably not less than 0.01 mm and notmore than 0.075 mm. It is favorable for the reflectance of the firstlight-modulating member 90 to be set to be less than the reflectance ofthe second light-modulating member 26 of the light source 20; forexample, it is favorable to be not less than 20% and not more than 90%for the light from the light source 20, and more favorably not less than30% and not more than 85%.

In the example shown in FIG. 2, a portion of the firstlight-transmitting member 80 that has a higher transmittance than thesecond and first light-modulating members 26 and 90 is interposedbetween the second light-modulating member 26 and the firstlight-modulating member 90. The light that is emitted from the lightsource 20, the light that is reflected by the first light-reflectivemember 41 at the periphery of the light source 20, etc., are guided intothe first light-transmitting member 80 between the secondlight-modulating member 26 and the first light-modulating member 90.Thereby, the region directly above the light source 20 can be not toobright and not too dark; as a result, the uneven luminance in thelight-emitting surface of the light-emitting region 301 can be reduced.

The first light-reflective member 41 increases the luminance of thelight that is extracted from the upper surface 11 that is located at thelower surface 12 side of the light guide plate 10 because the light thatis guided through the light guide plate 10 toward the lower surface 12side is reflected by the first light-reflective member 41 toward theupper surface 11 side that is the light-emitting surface of the planarlight source 300.

In the region between the first light-reflective member 41 and the uppersurface 11, the light from the light source 20 is guided through thelight guide plate 10 toward the partitioning groove 14 while repeatingtotal internal reflection at the first light-reflective member 41 andthe upper surface 11. A portion of the light traveling toward the uppersurface 11 is extracted outside the light guide plate 10 from the uppersurface 11.

As described above with reference to FIG. 3A, the first light-reflectivemember 41 includes the transmissive first resin member 41a, and thefirst reflector 41 b that has a lower refractive index than the firstresin member 41 a. Accordingly, the light that enters the first resinmember 41 a easily undergoes total internal reflection at the interfacebetween the first resin member 41 a and the first reflector 41 b. Thelight can be easily guided to regions distant from the light source 20by utilizing the total internal reflection of such a firstlight-reflective member 41. The light is easily guided to the entireregion of the light-emitting region 301 even when the distance betweenthe light source 20 and the end portion (the partitioning groove 14) ofeach light-emitting region 301 is long. The uneven luminance inside thelight-emitting surface (the upper surface 11) can be reduced thereby.Also, the number of the light sources 20 provided in the light guideplate 10 may be reduced.

It is favorable for the refractive index difference between the firstresin member 41 a and the first reflector 41 b to be large; inparticular, it is favorable for the first reflector 41 b to be a bubble(air).

The effect of suppressing the light that passes through the firstlight-reflective member 41 and escapes downward from the light-emittingmodule 100 increases as the thickness of the first light-reflectivemember 41 increases. The light that escapes downward from thelight-emitting module 100 is not extracted from the upper surface 11 andis lost. However, making the first light-reflective member 41 thickerimpedes thinning of the light-emitting module 100.

Therefore, according to the embodiment, the second light-reflectivemember 42 is located at the lower surface side of the firstlight-reflective member 41. As described above with reference to FIG.3B, the second light-reflective member 42 includes the transmissivesecond resin member 42 a, and the second reflector 42 b that has ahigher refractive index than the second resin member 42 a. The lightthat enters the second resin member 42 a can be reflected and scatteredby the second reflector 42 b; and the escape of light downward from thelight-emitting module 100 can be suppressed. In other words, bycombining the first light-reflective member 41 and the secondlight-reflective member 42 that has different reflectivecharacteristics, the escape of the light downward from thelight-emitting module 100 can be suppressed while ensuring thelight-guiding ability inside the light guide plate 10, and the lightextraction efficiency from the upper surface 11 can be increased.

Also, degradation of the wiring substrate 200 can be suppressed bysuppressing the light that escapes downward from the light-emittingmodule 100.

It is favorable for the refractive index difference between the secondresin member 42 a and the second reflector 42 b to be large; inparticular, titanium oxide is favorable as the second reflector 42 b.

It is favorable for the refractive index of the second resin member 42 aof the second light-reflective member 42 to be less than the refractiveindex of the first resin member 41 a of the first light-reflectivemember 41. Thereby, when light is incident on the second resin member 42a from the first resin member 41 a, the light easily undergoes totalinternal reflection at the interface between the first resin member 41 aand the second resin member 42 a; and the light that escapes downwardfrom the light-emitting module 100 can be further suppressed. Also, whenthe refractive index of the second resin member 42 a is low, therefractive index difference between the second resin member 42 a and thesecond reflector 42 b that has a higher refractive index than the secondresin member 42 a is large, and scattering reflections occur moreeasily.

The guidance of the light inside the light guide plate 10 is mainlyperformed by the first light-reflective member 41, and it is sufficientfor the second light-reflective member 42 to suppress the downwardescape of the light; therefore, the thickness of the secondlight-reflective member 42 may be less than the thickness of the firstlight-reflective member 41.

FIG. 16 is a graph illustrating measurement results of the reflectanceby wavelength for three test samples.

The solid line illustrates the measurement result of a first testsample. The first test sample had a structure in which a PET resin layerincluding bubbles was stacked with an acrylic resin layer including TiO2particles interposed on a glass substrate. The first test sample was astacked body of three layers, i.e., the glass substrate, the acrylicresin layer including TiO₂ particles, and the PET resin layer includingbubbles. The PET resin layer including bubbles corresponds to the firstlight-reflective member according to the embodiment; and the acrylicresin layer including TiO₂ particles corresponds to the secondlight-reflective member according to the embodiment. The thickness ofthe PET resin layer including bubbles was 50 μm; and the thickness ofthe acrylic resin layer including TiO₂ particles was 40 μm.

The broken line illustrates the measurement result of a second testsample. The second test sample had a structure in which a PET resinlayer including bubbles was stacked with an acrylic resin layer notincluding a light-diffusing agent such as a TiO₂ particle interposed ona glass substrate. The second test sample was a stacked body of threelayers, i.e., the glass substrate, the acrylic resin layer not includinga light-diffusing agent, and the PET resin layer including bubbles. Thethickness of the PET resin layer including bubbles in the second testsample was 188 μm and was greater than the thickness of the PET resinlayer including bubbles in the first test sample. The thickness of theacrylic resin layer not including a light-diffusing agent in the secondtest sample was 25 μm.

The dotted line illustrates the measurement result of a third testsample. The third test sample was a stacked body of the same threelayers as the second test sample; only the thickness of the PET resinlayer including bubbles was different from that of the second testsample. The thickness of the PET resin layer including bubbles in thethird test sample was equal to the thickness of the PET resin layerincluding bubbles in the first test sample, i.e., 50 μm.

The total thickness of the two layers on the glass substrate in thefirst test sample was less than the total thickness of the two layers onthe glass substrate in the second test sample. The total thickness ofthe two layers on the glass substrate in the first test sample was lessthan the thickness of the one layer of the PET resin layer includingbubbles in the second test sample. The thickness of the glass substratewas the same between the first, second, and third test samples. Thereflectances of the first, second, and third test samples were measuredfor multiple wavelengths from the bubble-including PET resin layer sideby using a high-speed spectrophotometer CMS-35SP of Murakami ColorResearch Laboratory Co., Ltd.

From the measurement result of FIG. 16, for the first test sample thatcorresponds to a configuration according to the embodiment, even thoughthe thickness of the PET resin layer including bubbles was less thanthat of the second test sample, the acrylic resin layer including TiO₂particles was formed under the PET resin layer including bubbles;therefore, the reflectance was equal to or greater than that of thesecond test sample in a wavelength band not less than about 430 nm andnot more than about 650 nm.

For the third test sample, the reflectance decreases toward thelonger-wavelength side of the light; for the first test sample, thedecrease of the reflectance was low even at the longer-wavelength side.

For example, to obtain a light source that can emit white light bycombining a red phosphor, a yellow phosphor, and a light-emittingelement that can emit blue light, the reflected yellow light and redlight of the first test sample can be greater than those of the thirdtest sample. Therefore, the same white light as the third test samplecan be obtained by the first test sample with a lower phosphor amountthan the third test sample; therefore, the phosphor cost can be reduced.The reflected green light of the first test sample can be greater thanthat of the third test sample when the light source includes onelight-emitting element that includes a light-emitting layer that canemit, for example, blue light and a light-emitting layer that can emit,for example, green light of a longer wavelength than the blue light.Therefore, in the first test sample, the green light amount can beprevented from being low with respect to the blue light; therefore,uneven color when used in a planar light source can be reduced.

In FIG. 1, when the X-direction is taken to be the row direction and theY-direction is taken to be the column direction, the planar light source300 shown in FIG. 1 includes six light-emitting regions 301 partitionedinto two rows and three columns. The luminance was measured and comparedfor a planar light source that included twenty-five light-emittingregions partitioned into five rows and five columns prototyped with theconditions of the first test sample described above and a planar lightsource that included twenty-five light-emitting regions similarlypartitioned into five rows and five columns prototyped with theconditions of the third test sample described above. As a result, theluminance of the planar light source prototyped with the conditions ofthe first test sample was about 7.7% greater than the luminance of theplanar light source prototyped with the conditions of the third testsample. From the reflectance measurement results shown in FIG. 16, itcan be seen that the reflectance difference between the first testsample and the third test sample was about 1 to 2%; however, thisreflectance difference has a greater effect on the luminance differencewhen used in a planar light source.

According to the embodiment, the reflectance of the lower surface 12side of the light guide plate 10 can be improved while thinning thelight-emitting module 100. The light extraction efficiency from theupper surface 11 of the light guide plate 10 can be increased thereby.

The first light-reflective member 41 faces the lower surface 12 of thelight guide plate 10 and the lower surface of the light source 20; andthe second light-reflective member 42 faces the entire lower surface ofthe first light-reflective member 41. In other words, the firstlight-reflective member 41 and the second light-reflective member 42 arelocated also at the bottom surface of the through-hole 13 in which thelight source 20 is located. The optical absorption of the regions underand at the vicinity of the light source 20 can be reduced thereby.

A method for manufacturing the planar light source 300 will now bedescribed with reference to FIGS. 5 to 13.

The method for manufacturing the planar light source 300 according tothe embodiment includes a process of preparing a structure body 200′shown in FIG. 5. The structure body 200′ is the structure body of thewiring substrate 200 described above before forming the conductivemember 60.

As shown in FIG. 6, a structure body 400 is formed by disposing astacked sheet 40 on the structure body 200′. The stacked sheet 40includes the second light-reflective member 42 that is located on thesecond insulating layer 51 of the structure body 200′, the firstlight-reflective member 41 that is located on the secondlight-reflective member 42, and the bonding member 71 that is located onthe first light-reflective member 41.

As shown in FIG. 7, the hole 401 is formed in the structure body 400.The hole 401 extends through the bonding member 71, the firstlight-reflective member 41, the second light-reflective member 42, thesecond insulating layer 51, and the insulating base 50. For example, thehole 401 may formed with a drill, or by punching or laser patterning.Alternatively, the hole 401 may be formed to continuously extend throughthe bonding member 71, the first light-reflective member 41, the secondlight-reflective member 42, the second insulating layer 51, and theinsulating base 50 by procuring the bonding member 71, the firstlight-reflective member 41, the second light-reflective member 42, thesecond insulating layer 51, and the insulating base 50 (the firstinsulating layer 52, the first wiring layer 53, and the second wiringlayer 54 being bonded to each other in the insulating base 50) in whichholes are formed and by bonding these components. Alternatively, thestructure body 400 may be prepared by procuring the structure body 400in which the hole 401 is preformed.

As shown in FIG. 8, the light guide plate 10 is located on the structurebody 400 in which the hole 401 is formed. The lower surface 12 of thelight guide plate 10 is bonded to the bonding member 71. Thethrough-hole 13 is formed in the light guide plate 10; and thethrough-hole 13 is positioned to overlap the hole 401.

As shown in FIG. 9, the light source 20 is disposed in the through-hole13. The lower surface of the cover member 24 that is the lower surfaceof the light source 20 is bonded to the upper surface of the firstlight-reflective member 41 that is exposed in the through-hole 13. Theelectrode 23 of the light source 20 is aligned with the hole 401. Atleast a portion of the lower surface of the electrode 23 is exposed inthe hole 401.

After the light source 20 is disposed, a light-transmitting member 81 isformed in the through-hole 13 as shown in FIG. 10. Thelight-transmitting member 81 is formed between the side surface of thelight source 20 and the inner side surface of the through-hole 13. Forexample, the light-transmitting member 81 is formed by supplying aliquid light-transmitting resin to the through-hole 13 and bysubsequently curing. It is favorable for the heating temperature whencuring the light-transmitting resin to be not less than 30° C. and notmore than 150° C., and more favorably not less than 40° C. and not morethan 130° C. The side surface of the light source 20 is covered with thelight-transmitting member 81; and the upper surface of the light source20 is not covered with the light-transmitting member 81 in thethrough-hole 13.

After the light-transmitting member 81 is formed in the through-hole 13,the partitioning groove 14 is formed in the light guide plate 10 asshown in FIG. 11. In the example shown in FIG. 11, the partitioninggroove 14 extends through the light guide plate 10 and reaches a portionof the structure body 400. For example, the partitioning groove 14 isformed by cutting. The gap between the side surface of the light source20 and the inner side surface of the through-hole 13 is filled with thelight-transmitting member 81; therefore, cutting chips of thepartitioning groove 14 can be prevented from entering the gap.

After the partitioning groove 14 is formed, the first conductive portion61 is formed in the hole 401. As shown in FIG. 12, for example, aconductive paste is supplied to the hole 401 in a state in which thestructure body 400 is positioned higher than the light guide plate 10and the light source 20. The first conductive portion 61 that isconnected with the electrode 23 of the light source 20 is formed bycuring the conductive paste. The second conductive portion 62 is formedon the surface of the insulating base 50 at which the first wiring layer53 is formed to be connected to the first wiring layer 53 and the firstconductive portion 61. For example, the second conductive portion 62 isformed by supplying a conductive paste onto the surface of theinsulating base 50 by subsequently curing. For example, the firstconductive portion 61 and the second conductive portion 62 are formed tohave a continuous body in the same process. In such a case, the lightsource 20 is already bonded to the bonding member 71; therefore, theconductive paste does not enter between the bonding member 71 and thelower surface of the light source 20. Short-circuits between theelectrodes 23 via the conductive paste can be prevented thereby.

After the conductive member 60 is formed, a light-transmitting member 82shown in FIG. 13 is formed on the light-transmitting member 81 and onthe light source 20 in the through-hole 13. Thereby, the through-hole 13is filled with the first light-transmitting member 80 that is made ofthe light-transmitting members 81 and 82.

For example, the light-transmitting member 82 is formed by supplying aliquid light-transmitting resin to the through-hole 13 and bysubsequently curing. In such a case, color tone correction is possibleby dispersing a phosphor 83 inside the light-transmitting resin.

For example, the light-emitting element 21 is caused to emit light bysupplying a current to the light-emitting element 21 via the conductivemember 60 in the state of FIG. 12. The phosphor that is included in thesecond light-transmitting member 25 is excited by the light emitted bythe light-emitting element 21 and emits light. In other words, the colorof the light emitted by the light source 20 is a mixed color of thecolor of the light emitted by the light-emitting element 21 and thecolor of the light emitted by the phosphor, and the chromaticity of thelight of the light source 20 is measured. The chromaticity can becorrected to the target chromaticity by mixing an appropriate amount ofthe phosphor 83 into the light-transmitting member 82 according to themeasurement result of the chromaticity. The phosphor for chromaticitycorrection may be mixed into the light-transmitting member 81 whenforming the light-transmitting member 81 in the through-hole 13 in theprocess shown in FIG. 10.

After the through-hole 13 is filled with the first light-transmittingmember 80, the third light-reflective member 43 is formed in thepartitioning groove 14 as shown in FIG. 2. The first light-modulatingmember 90 is formed on the first light-transmitting member 80. The thirdlight-reflective member 43 and the first light-modulating member 90 canbe simultaneously formed from the same material. For example, the thirdlight-reflective member 43 and the first light-modulating member 90 canbe formed by printing or inkjet.

FIG. 4B is a schematic cross-sectional view of another example of thelight source.

The cover member 24 covers the side surface and lower surface of thesemiconductor stacked body 22 of the light-emitting element 21. Thesecond light-transmitting member 25 is located on the upper surface ofthe semiconductor stacked body 22. The second light-transmitting member25 is located also on the cover member 24 that covers the side surfaceof the semiconductor stacked body 22. The second light-modulating member26 is located on the second light-transmitting member 25. According tothe desired light distribution, the second light-modulating member 26 isnot necessarily provided on the second light-transmitting member 25.

FIG. 4C is a schematic cross-sectional view of another example of thelight source.

The light source shown in FIG. 4C includes the light-emitting element 21and the second light-modulating member 26 that is located at the uppersurface of the light-emitting element 21, but does not include thesecond light-transmitting member 25 and the cover member 24 describedabove. According to the desired light distribution, the secondlight-modulating member 26 is not necessarily provided at the uppersurface of the light-emitting element 21.

FIG. 14 is a schematic cross-sectional view of one portion of a planarlight source according to another embodiment of the invention. FIG. 14illustrates a cross section including a portion of the planar lightsource where the light source 20 is located and a peripheral portion ofthe planar light source.

The light guide plate 10 includes a bottomed hole portion 15 having aconcave cross-section that is open at the lower surface 12 side.According to the embodiment, the hole portion 15 is atruncated-circular-conical space and can also be, for example, atruncated-polygonal-pyramid space that has a truncated rectangularpyramid shape, a truncated hexagonal pyramid shape, etc. The lightsource 20 is located in such a hole portion 15. A light-reflectivemember 45 is located between the inner side surface of the hole portion15 and the side surface of the light source 20. The light-reflectivemember 45 is, for example, a resin member that includes alight-diffusing agent.

A recess 16 is formed in the upper surface 11 side of the light guideplate 10 at a position facing the hole portion 15. For example, a recessthat has a polygonal pyramid shape such as a circular cone, arectangular pyramid, a hexagonal pyramid, or the like, a recess that hasa truncated polygonal pyramid shape such as a truncated circular cone, atruncated rectangular pyramid, a truncated hexagonal pyramid, etc., areexamples of the recess 16. Also, a first light-modulating member 46 islocated in the recess 16. The first light-modulating member 46 has aconfiguration similar to that of the first light-modulating member 90described above.

Similarly to embodiments described above, the first light-reflectivemember 41 is located at the lower surface 12 side of the light guideplate 10, and the second light-reflective member 42 is located at thelower surface side of the first light-reflective member 41.

A light-reflective member 44 is located at the peripheral region of thelight source 20 of the lower surface 12 of the light guide plate 10 andat the lower surface of the light-reflective member 45. Thelight-reflective member 44 is, for example, a resin member that includesa light-diffusing agent.

The electrode 23 of the light source 20 is connected to a wiring layer56 of a wiring substrate 210. The wiring substrate 210 includes aninsulating base 55, and the wiring layer 56 that is formed on theinsulating base 55. The first light-reflective member 41 and the secondlight-reflective member 42 are located between the wiring substrate 210and the lower surface 12 of the light guide plate 10.

In the planar light source shown in FIG. 14 as well, by combining thefirst light-reflective member 41 and the second light-reflective member42 that have different reflective characteristics, the light thatescapes downward from the light guide plate 10 can be suppressed whileensuring the light-guiding ability inside the light guide plate 10; andthe light extraction efficiency from the upper surface 11 can beincreased.

FIG. 15 is a schematic cross-sectional view of one portion of a planarlight source according to another embodiment of the invention.

The planar light source is an edge-type planar light source; and thelight source 20 faces an end surface 17 of the light guide plate 10. Theend surface 17 of the light guide plate 10 is a light incident surfaceon which the light from the light source 20 is incident, and alight-emitting surface 20 a of the light source 20 faces the end surface17 of the light guide plate 10.

The light source 20 and the light guide plate 10 are located in a case500. A wiring substrate 220 is located between the light source 20 and abottom wall 501 of the case 500; and the light source 20 is mounted onthe wiring substrate 220.

The lower surface 12 of the light guide plate 10 faces the bottom wall501 of the case 500, and the first light-reflective member 41 and thesecond light-reflective member 42 described above are located betweenthe lower surface 12 of the light guide plate 10 and the bottom wall 501of the case 500. The first light-reflective member 41 is located at thelower surface 12 side of the light guide plate 10, and the secondlight-reflective member 42 is located at the lower surface side of thefirst light-reflective member 41.

In the planar light source shown in FIG. 15 as well, by combining thefirst light-reflective member 41 and the second light-reflective member42 that have different reflective characteristics, it is possible tosuppress the escape of light downward from the light guide plate 10while ensuring the light-guiding ability inside the light guide plate10, and to increase the light extraction efficiency from the uppersurface 11.

In the embodiments described above, the second light-reflective member42 that has a higher reflectance than the first light-reflective member41 can be located at the lower surface side of the firstlight-reflective member 41; for example, a metal film, a dielectricmultilayer film, etc., can be used as the second light-reflective member42.

Also, an air layer can be used as a light guide member that correspondsto the light guide plate 10.

In the method for manufacturing the planar light source 300 describedabove, after forming the first conductive portion 61 in the hole 401 ofthe structure body 400 shown in FIG. 7, the light guide plate 10 may bedisposed on the structure body 400, and the light source 20 may bedisposed in the through-hole 13 of the light guide plate 10. Thereafter,the process of forming the light-transmitting member 81 in thethrough-hole 13, the process of forming the partitioning groove 14 inthe light guide plate 10, the process of forming the second conductiveportion 62, etc., are continued.

In the method for manufacturing the planar light source 300 describedabove, the first light-transmitting member 80 may be disposed in thethrough-hole 13 to cover the light source 20 after forming the firstconductive portion 61 in the hole 401 of the structure body 400 shown inFIG. 9. In such a case, for example, the process of forming thepartitioning groove 14 in the light guide plate 10 can be performedafter disposing the light guide plate on the structure body 400 shown inFIG. 8 and before disposing the light source 20 in the through-hole 13of the light guide plate 10 shown in FIG. 9. The firstlight-transmitting member 80 may include the multiple light-transmittingmembers 81 and 82 or may include a single-layer light-transmittingmember. The single-layer light-transmitting member can include, forexample, the phosphor, the light-diffusing agent, etc., described above.

Embodiments of the present invention have been described with referenceto specific examples. However, the present invention is not limited tothese specific examples. Based on the above-described embodiments of thepresent invention, all embodiments that can be implemented withappropriately design modification by one skilled in the art are alsowithin the scope of the present invention as long as the gist of thepresent invention is included. Further, one skilled in the art canconceive various modifications that fall within the scope of the presentinvention.

What is claimed is:
 1. A light-emitting module comprising: a lightsource; a light guide plate including an upper surface and a lowersurface, the lower surface being at a side opposite to the uppersurface, the light guide plate being configured to guide light from thelight source; a wavelength conversion sheet located at an upper surfaceside of the light guide plate; a first light-reflective member locatedat a lower surface side of the light guide plate, wherein the firstlight-reflective member comprises: a first resin member, and a firstreflector, wherein a refractive index of the first reflector is lowerthan a refractive index of the first resin member; and a secondlight-reflective member located at a lower surface side of the firstlight-reflective member, wherein the second light-reflective membercomprises: a second resin member, and a second reflector, wherein arefractive index of the second reflector is higher than a refractiveindex of the second resin member.
 2. The module according to claim 1,wherein: the wavelength conversion sheet includes a red phosphor and agreen phosphor.
 3. The module according to claim 1, wherein: thewavelength conversion sheet includes a first wavelength conversion sheetincluding a red phosphor, and a second wavelength conversion sheetincluding a green phosphor.
 4. The module according to claim 2, wherein:the red phosphor is a fluoride-based phosphor or a quantum dot phosphor.5. The module according to claim 3, wherein: the red phosphor is afluoride-based phosphor or a quantum dot phosphor.
 6. The moduleaccording to claim 2, wherein: the green phosphor is a phosphor having aperovskite structure or a quantum dot phosphor.
 7. The module accordingto claim 3, wherein: the green phosphor is a phosphor having aperovskite structure or a quantum dot phosphor.
 8. The module accordingto claim 1, wherein: the first reflector is a bubble.
 9. The moduleaccording to claim 1, wherein: the second reflector is a titanium oxideparticle.
 10. The module according to claim 1, wherein: the refractiveindex of the second resin is lower than the refractive index of thefirst resin member.
 11. The module according to claim 1, wherein: thefirst resin member is formed of a polyethylene terephthalate resin, anolefin resin, an acrylic resin, a silicone resin, a urethane resin, oran epoxy resin.
 12. The module according to claim 1, wherein: the secondresin member is formed of an acrylic resin, a silicone resin, a urethaneresin, or an epoxy resin.
 13. The module according to claim 1, wherein:a thickness of the second light-reflective member is less than athickness of the first light-reflective member.
 14. The module accordingto claim 1, wherein: the first light-reflective member faces the lowersurface of the light guide plate and a lower surface of the lightsource.
 15. The module according to claim 14, wherein: the secondlight-reflective member faces an entire lower surface of the firstlight-reflective member.
 16. The module according to claim 1, wherein:the light guide plate includes a hole portion, and the light source islocated in the hole portion.
 17. The module according to claim 16,wherein: the hole portion is a bottomed hole portion that is open at thelower surface side of the light guide plate.
 18. The module according toclaim 16, wherein: the hole portion is a through-hole extending from theupper surface to the lower surface of the light guide plate.
 19. Aplanar light source, comprising: the light-emitting module according toclaim 1; and a wiring substrate; wherein the first light-reflectivemember and the second light-reflective member are located between thewiring substrate and the lower surface of the light guide plate.